Extremely Dangerous Large Enclosed Structure Fires

Eventually, the entire interior of the structure becomes untenable as the flashover stage is reached.

Photo credit: Photo Courtesy of Stewart English

After air is initially drawn into the structure when horizontal venting is completed, heavy pressurized smoke begins to vent from the Alpha side of the structure.

Photo credit: Photo Courtesy of Stewart English

As heavy smoke fills the structure, windows on the Alpha side are vented.

Photo credit: Photo Courtesy of Stewart English

With an 11 mph wind striking the Charlie side of this large enclosed structure, Charleston Firefighters implemented a fast attack from the unburned side (the Alpha side). As blinding smoke conditions set in, nine Firefighters, who were separated from a handline, became disoriented, depleted their air supply and were unable to exit the structure.

Photo credit: Photo Courtesy of Stewart English

The tragic event that unfolded in Charleston, SC, on June 18, 2007, marked the worst case of firefighter disorientation ever recorded in the United States. Since the details surrounding the deaths of nine firefighters have a direct and immediate impact on firefighter safety, Firefighters should never forget what transpired there. More importantly, firefighters must learn from this landmark incident and institute changes in order to avoid similar results from occurring in their department. Since new information has been collected over the years about these specific types of fatal structure fires, a discussion about the strategy and tactics used during this fire and others like it, is absolutely necessary.

Ineffectiveness Of The Current ApproachIn general and based on the teachings and traditions of the fire service, firefighters nationwide currently manage structure fires in the same way. Depending on the initial size-up factors seen on arrival, and if relatively safe, firefighters will either quickly and aggressively attack the fire from the unburned side or when conditions are unsafe, a defensive, exterior attack will be utilized. This is an easy and highly logical method of operation and has served the fire service relatively well over the years. A problem with this method of operation however, has been identified and linked to line-of-duty deaths. While a fast and aggressive interior attack may be safe and effective to utilize on certain types of structures such as a small or moderate size residence without a basement, it is now known that an offensive strategy cannot be relied upon for safe and effective use on all structure fires. Since the problem structure has been identified, it must therefore be known by every active firefighter today and in the future.

The Enclosed Structure: Significance Of The Structural DesignOne of several findings revealed by the U.S. Firefighter Disorientation Study was that in 100 percent of the cases examined, the structures in which disorientation occurred had an enclosed structural design. And in conjunction with other findings, a clear understanding associated with enclosed structure fires concerning the loss of safety and ineffectiveness of the initial size-up, the strategy, the tactics and tasks were determined. Concerning the fundamental architectural design of a structure, it was found that an absence of an adequate number of openings such as windows and doors was shown to have major ramifications in the safety and effectiveness of firefighters who used traditional offensive strategies. And the reason this should be of serious concern to the active firefighter today is because today's firefighters have been trained, equipped and expected to initiate a fast and aggressive interior attack from the unburned side of a structure without factoring the extreme danger associated with an enclosed structural design and of the smoke and extreme fire behavior it is highly prone to produce. Additionally, according to the report, Analysis of Structural Firefighter Fatality Database, should the enclosed structure not be protected by an operable sprinkler system, that crew and subsequent crews entering the structure have a 77 percent chance of being exposed to life threatening hazards that may disorient and take their lives and a staggering 84 percent chance of being victims of a multiple firefighter fatality event. The reality is that all of these findings pertained to the Charleston incident and to many previous structure fires which were large in size, and which also had an enclosed design.

The Firefighter Disorientation SequenceIn any occupation involving a serious injury or fatality, a chain of events leading to the unfavorable outcome can be identified. If one link in the chain can be broken, the injury or fatality can be prevented. One such chain identified with interior structural firefighting is the Firefighter Disorientation Sequence, also uncovered during the disorientation study. It typically involves safe but uninformed firefighters quickly executing established strategies and tactics cited in their standard operating procedures. In general, the steps in the sequence include:

Fire in an enclosed structure with smoke showing

A fast and aggressive interior attack

Deteriorating conditions

Handline separation or entangled handines encountered

Disorientation

During the early stage of the Charleston fire, heavy smoke and fire was visible from the rear, or Delta side of the structure and an attack with the use of a handline was quickly initiated. Due to deteriorating conditions however, the crew evacuated and the attack was subsequently made from the exterior. During this effort, entry was also made from the Alpha side and an investigation of the interior found it to be clear with the exception of light smoke seen at the ceiling at the right rear of the store. Subsequently, a deep interior attack was made from the unburned side of the structure in an attempt to cut off fire spread into the main areas of the structure. As conditions deteriorated, heavy smoke gradually filled the interior resulting in prolonged zero visibility conditions. Those firefighters working on the interior of the structure at that time and without the benefit of a handline, to serve as a lifeline out of the structure, became disoriented and depleted there air supplies attempting to reach the safety of the exterior. Thus, the disorientation sequence tragically unfolded in Charleston. The interior of the store then flashed over followed by a collapse of major portions of the roof.

A Multitude Of FactorsAny working fire involves a multitude of fireground factors which are considered by arriving firefighters during the initial size-up and throughout the course of the fire. Many factors are routinely considered and may have no bearing on the incident. Others however, which may be critical to the incident, may on occasion be seriously overlooked.

In addition to such size-up factors as the time of day, the type of occupancy, the type of construction, the use of truss construction, the life hazard present as well as the amount and location of fire and smoke showing on arrival, other important factors must always be considered. One factor pertains to whether the involved structure has an opened or an enclosed architectural design. An opened structure has an adequate number of windows or doors to allow prompt ventilation and emergency evacuation of firefighters. The opposite is true however, with an enclosed structure. An enclosed structure does not have enough windows or doors for ventilation or emergency evacuation and for this reason should be considered extremely dangerous. In addition, it must be clearly understood that during fast and aggressive interior attacks, enclosed structures have exposed firefighters to life threatening hazards such as violent flashovers, backdrafts, collapses of roofs and floors and to prolonged zero visibility conditions, any of which may cause disorientation which may lead to firefighter fatalities.

A second factor pertains to the size of the structure, while a third pertains to the weather. In regards to the weather, this is associated with firefighter awareness of the wind speed, direction and of any possible changes that may occur during the course of the incident and of the impact it may have on the incident action plan. In objective terms, The Charleston incident was one of the most dangerous type of enclosed structure fire for the following reasons.

The Sofa Super Store building fell into the category of an enclosed structure in which the associated danger was not recognized. It was a large enclosed structure defined as one measuring greater than 100-by-100 feet in size which adds to the overall complexity of an incident. Enclosed structures of this and greater size have been associated with numerous multiple firefighter fatality events in the past. And finally, the Charleston tragedy, like the Phoenix grocery store fire of 2001, was not only a large enclosed structure fire, it hampered firefighters because it was also a wind driven structure fire which initially caused prolonged zero visibility conditions and eventually pushed the heat and fire to the broken windows and opened doors at the point of entry which served as vents points for the products of combustion. This situation in both incidents, placed firefighters, who were initiating an attack from the unburned side, in the flow path of smoke, heat and fire which eventually forced them out as fire rapidly consumed all of the fuel in its path.

The National Institute of Standards and Technology, (NIST), has recently described the hazard associated with wind driven fires in high-rise structures. With exterior winds of 10 to 15 mph, temperatures measured in hallways adjacent to room fires exceeded 1,100 degrees F in the flow path of fire gases and heat. This represented an environment in which full personal protective equipment would not provide a firefighter required protection for safety. Additionally, there is sufficient evidence to show that the hazard can involve structures of opened or enclosed design not only in high-rise structure fires but in structure fires taking place on grade level as well.

Wind driven fires occurring in structures not categorized as high-rise structures have taken place on grade level in residences in Prince William County, VA and Baytown, TX, and others including a restaurant in Carthage, MO, a church in Lake Worth, TX and most recently in a millwork warehouse in Salisbury, NC. In these scenarios, and after factoring in the possible life hazard present, the recommendation offered by NIST which calls for attacking the fire with the wind at your back can be applied to prevent line-of-duty-deaths in these grade level wind driven fires, whether they occur during an opened or enclosed structure fire.

Enclosed Structure Tactics Needed NowThe consequences of using a fast and aggressive interior attack from the unburned side into a large enclosed structure are well documented. Study has shown that an offensive strategy used at these structures, without the wind hazard, will typically end in defensive operations and firefighter disorientation which leads to line-of-duty-deaths. In order to manage the risk on the fireground, all incident commanders, officers and firefighters must learn to recognize and appreciate the extreme danger associated with enclosed structures of all sizes. They must also understand that traditional initial size-up factors are being misinterpreted and that the use of a fast and aggressive interior attack from the unburned side may result in firefighter disorientation.

Therefore, the use of Enclosed Structure Standard Operating Guidelines, unique to the resources of each department, and which are programmed to avoid the risk during large enclosed structure fires must be developed and implemented. In light of the fact that traumatic Firefighter fatalities are continuing to occur in enclosed structure fires, tactics dedicated to enclosed structure fires are immediately needed on the fireground. These tactics, which are completely understood by all responders and incorporate all nationally recognized policies and practices including use of the incident command system and an accountability system, methodically ensure that:

An enclosed structure is involved

Life hazard is not present

Accurate size-up including a 360-degree walk around is completed

A cautious interior assessment of conditions is conducted

A safety based decision is reached

One of three tactics is selected including:

An attack from the point of entry

An attack from a different side of the structure which is closer to the seat of the fire (short interior attack)

A defensive attack is initiated

Adequate support is provided, including establishment of a supply line, back-up companies with handlines or interior master streams, Rapid intervention teams, safety officers, thermal imagers, coordinated ventilation which controls the inlet and vent points of air and provides ventilation which will not cause a flashover or backdraft while crews are on the interior, forcible entry and breaching of exterior or interior adjoining walls.

A risk management statement describing the acceptable risk is followed.

ConclusionFirefighters have always adapted and overcome when confronted with significant problems on the fireground. The large enclosed structure fire is the latest challenge. However, with progressive leadership and commitment from all levels of the fire service including local, state and national, it can and must be done again.

Note:The preceding article implements the National Fallen Firefighters Foundations' Life Safety Initiative # 3: Focus greater attention on the integration of risk management with incident management at all levels, including strategic, tactical, and planning responsibilities.

WILLIAM R. MORA, a Firehouse.com Contributing Editor, is a Captain in the firefighting division of the San Antonio, TX, Fire Department. William has done extensive research on the topic of firefighter disorientation including the analysis of 444 structural firefighter fatalities and is the author of the United States Firefighter Disorientation Study 1979-2001. To read William's complete biography and view his archived articles, click here. You can reach William by e-mail at capmora@aol.com.